Method for screening and treating a subject for a cancer

Abstract

The present invention relates to the diagnostic of cancerous subject. Indeed, the inventors observed by using a Q-PCR based methods and sequencing methods that quantification of specific single stranded DNA fragments obtained from cell free nucleic acids (cfDNA) may discriminate cfDNA from healthy and cancer derived subjects. Single stranded DNA fragments obtained from CfDNA or specific range of single stranded DNA fragments are rather lower or higher when derived from healthy subject than from cancer subject. More, specific ratios for different size or range of single stranded DNA fragments varies between cancer subjects and healthy individuals. These values are sufficiently and significantly different to be used as values to determine whether a human subject may have cancer or not as a screening test. Thus, the invention relates to a method for screening a subject for a cancer comprising the steps of extracting and denaturing cfDNA, determining the single strand fragment level upon their size distribution, and calculate these former values to screen an individual for cancer.

The invention claimed is: 
     
       1. A method for treating cancer in a subject in need thereof, comprising the steps of:
 i) extracting cell free DNA from a sample obtained from a subject; 
 ii) denaturating the cell free DNA to obtain single stranded DNA fragments; 
 iii) determining the levels of single stranded DNA fragments having a length ranging from 98 to 158 nucleotides and from 168-218 nucleotides; and 
 iv) administering one or more cancer treatments to a subject identified as having 
 a higher level than a predetermined reference value of at least one single stranded DNA fragment ranging from 98 to 158 nucleotides, and 
 a lower level than a predetermined reference value of at least one single stranded DNA fragment having a length ranging from 168 to 218 nucleotides; 
 wherein the one or more cancer treatments are selected from the group consisting of radiotherapy, chemotherapy, and immunotherapy. 
 
     
     
       2. The method of  claim 1 , wherein the cancer is colorectal cancer. 
     
     
       3. The method of  claim 2 , wherein the colorectal cancer is metastatic colorectal cancer.